How old am I if 500 reduced by 2 times my age is 310? How old am I if 400 reduced by 4 times my age is 40?

How old am I if 200 reduced by 2 times my age is 4?

The amount cami raised during last year’s charity walk, $45.50, is 7/10 of the amount she raised this year. which equation represents n, the number of dollars she raised this year?