143=7+8 (3-7x) solve and justify

Justify means plug answer in and verify

so distribute 8 (3-7x) = 24-56x

143=7+24-56x

143=31-56x

minus 31 both sides

112=-56x

divide both sides by - 56

-2=x

justify

plug it back

143=7+8 (3-7x)

143=7+8 (3-7 (-2))

143=7+8 (3 - (-14))

143=7+8 (3+14)

143=7+8 (17)

143=7+136

143=143

true

x=-2