Just need someone to explain how
I simplified it to -2a+15b/ 4

Answer:
Step-by-step explanation:
3(4a + 6b) = 3*4a + 3*6b = 12a + 18b
-2(7a + b) = -2*7a + (-2)*b = -14a - 2b
[tex]\frac{5[3(4a+6b)-2(7a+b)-b]}{20}=\frac{5[12a+18b-14a-2b-b]}{20}\\\\ \frac{5[-2a+15b]}{20}=\frac{15b-2a}{4}[/tex]
x =1/4
X = 1/4 ?
since multiplying fractions is straight across,
1/4 * (15b -2a) would result in the simplification you got.