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**mathshelpneeded** Hello please help!

The rate at which material decays is given in the differential equation where

**x** is the grams present after **t** days.

dx/dt = -kx

The half life of a radioactive material is roughly 25 days.

find the time taken for 100g of the material to decay.

I know you intergrate the equation by swapping x over to the left to get 1/x and dt over to the right to get -kdt. and i integrated the two sides, but when i "plugged" all the numbers in, it never worked out. the answer is...58 days, please help!