Answer:
20
Step-by-step explanation:
3x + 4x - 15
3(5)+4(5) - 15
15 + 20 - 15
You can add the oposites
15 + (-15)
= 0
And then you have 20 left. Or add 15 + 20 = 35 then subtract 15 (which equals 20)
Hope this helps!
84 percent I think