We need to give the mystery number an easy name so that
we can work with it. Let's call it it ' M ' , for 'mystery number'.
The number . . . . . . . . . . . . . M
3/4 of it . . . . . . . . . . . . . . . . . 3/4 M
the sum of 3/4 of it and 1 . . . (3/4 M + 1)
You said that sum is equal to -5 .
OK. The equation we need to solve is
3/4 M + 1 = - 5
Subtract 1 from each side: 3/4 M = - 6
Multiply each side by 4 : 3 M = -24
Divide each side by 3 : M = - 8
Does it work ?
Check it :
-- Assume the mystery number is . . . -8 .
-- 3/4 of the number . . . . . . . . . . . . . - 6 .
-- sum of 3/4 of the number and 1 . . . -5 <== yay !
