Answer:
x=3 and x=-1.25
Explanation:
4x^2-7x=15
subtract 15 from each side:
4x^2-7x-15=0
factor (trying different numbers that the sum is 7 and the quotient is 15)
(2x-6 )(2x+2.5 )=0
2x-6=0 add 6 to each side
2x=6
x=3
2x+2.5=0 subtract 2.5 from each side
2x=-2.5
x=-1.25