Who can solve the equation 5x △ 15 = 158x-0.5x = 30

Who can solve the equation 5x △ 15 = 158x-0.5x = 30

5x÷15=15
5x=15×15
x=225÷5
x=45
8x-0.5x=30
7,5x=30
x=30÷7.5
x=4