Answer:
DF = 57
Step-by-step explanation:
(4x + 10) + (2x - 1) = 9x - 15
add like terms: 6x + 9 = 9x - 15
add 15 to both sides: 6x + 24 = 9x
subtract 6x: 3x = 24
divide by 3: x = 8
plug x = 8 into 9x - 15:
9(8) - 15
= 72 - 15
= 57
You can also check the answer by plugging x = 8 into the other equations and adding them:
4(8) + 10 + 2(8) - 1
= 32 + 10 + 16 - 1
= 42 + 15
= 57 ✅
