If the natural recharge rate of an aquifer is 1 centimeter per year, but the rate of groundwater pumping is 15 centimeters per year, how far will the water table drop in 10 years?

2.Assuming the natural recharge rate of 0.5 centimeters per year, if groundwater pumping lowers the water by 50 centimeters, how many years of ‘fossil water’ have been extracted?

I assume this isn’t homework.
15 cm/year * 10 years = 150 cm.
150cm - (1cm * 10 years) = 140 cm total water table drop in 10 years.
50cm / (.5cm/yr) = 100 years.

I assume it is, especially given that the two questions use different recharge rates, and that the title says “earth science”, which is probably the name of the course that this would be assigned in.

But one of your answers is wrong, anyway. Finding the mistake, I leave as an exercise for the student.