112= 7x + 7(-4x-17)
multiply the 7 by everything in parentheses
112=7x+(7*-4x)+(7*-17)
Positive multiplied by a negative is negative
112=7x-28x-119
combine like terms
112= -21x-119
add 119 to both sides
231= -21x
divide both sides by -21
-11= x
Check:
Substitute answer in equation
112= 7x + 7(-4x-17)
112= 7(-11)+7[(-4)(-11)-17]
112= -77 + 7(44-17)
112= -77 + 7(27)
112= -77 + 189
112=112
Hope this helps! :) Good luck with math!!