m/5 + 8 = -7

\(\displaystyle \begin{array}{rcl}
\frac{m}{5} + 8 & = & - 7 \\
\frac{m}{5} & = & - 7 - 8 \\
\frac{m}{5} & = & - 15 \\
m & = & - 75 \\
\\
\end{array}\)
 
Mom, remember that if a/b = c/d, then ad = bc ; crisscross multiplication

If you have a/b = c, same thing: a/b = c/1; so a(1) = bc, a = bc

Same with m/5 = -15 ; m/5 = -15/1 : m(1) = 5(-15) : m = -75

Yokay?
 
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