MATLAB: How to find these values using polyfit command

Question

Alright , so i have the values of t time respectively first colum and R radioactive decay which corresponds to second colum (look below ) . The formula of radioactive decay is R=R0 * e^(-λt). Now I wanted to know if there is any way to find the values of R0 and λ for each case by using command polyfit ?

Does anybody have an idea how can I do this?

Thank you & Have a great day.

Values : 10       312
        11       328
        12       311
        13       290
        14       283
        15       285
        16       255
        17       291
        18       271
        19       272
        20       253
        21       255
        22       263
        23       246
        24       264
        25       213
        26       261
        27       241
        28       228
        29       242
        30       215
        31       192
        32       206
        33       182
        34       188
        35       197
        36       195
        37       180
        38       210
        39       176
        40       183
        41       199
        42       159
        43       171
        44       166
        45       145
        46       181
        47       177
        48       137
        49       149
        50       185
        51       148
        52       149
        53       142
        54       150
        55       140
        56       149
        57       123
        58       112
        59       118
        60       145
        61       146
        62       118
        63       113
        64       120
        65       126
        66       120
        67       125
        68       114
        69       114
        70       117
        71       103
        72       102
        73        96
        74        97
        75       102
        76       117
        77       114
        78        88
        79        94
        80       101
        81        93
        82       113
        83        74
        84        78
        85        81
        86       102
        87        94
        88        93
        89        81
        90        64
        91        88
        92        81
        93        96
        94        72
        95        82
        96        81
        97        71
        98        71

Answer 1

When R=R0 * e^(-λt) then log( R) = log(R0 * e^(-λt)) so log( R) = log(R0) + log(e^(-λt)) so log( R) = log(R0) - λ*t . This gives us a simple linear fit,

P = polyfit(t, log( R), 1);

and then λ = P(1) and log(R0) is P(2)