Mr. Thompson weighs 260 pounds and he loses 4 pounds each month.
The equation will be :
w = 260 - 4m
where w is the weight after m months
when w = 220 pounds, the number of months will be :
220 = 260 - 4m
4m = 260 - 220
4m = 40
m = 40/4
m = 10
The answer is 10 months
