math
posted by steven on .
Salma's penny bank is 1/2 full. After she adds 360 pennies, it is 4/5 full. How many pennies can Salma's bank hold?

1/2 = 5/10
4/5 = 8/10
8/10  5/10 = 3/10
3/10x = 360
x = 360 / (3/10)
x = 360 * 10/3
x = 1200 
( 1 / 2 ) x + 360 = ( 4 / 5 ) x
360 = ( 4 / 5 ) x  ( 1 / 2 ) x
360 = ( 8 / 10 ) x  ( 5 / 10 ) x
360 = ( 3 / 10 ) x
( 3 / 10 ) x = 360 Multiply both sides by 10
3 x = 360 * 10
3 x = 3600 Divide both sides by 3
x = 3600 / 3
x = 1200 pennies