3-2(9+2m)=m — step-by-step solution

Let's solve in

ℝ

3 - 2 \cdot (9 + 2 m) = m

ⓘ Expand by multiplying each term inside the parentheses:

- 2 \cdot (9 + 2 m)

- (18 + 4 m)

3 - (18 + 4 m) = m

ⓘ A minus sign before a parenthesis changes the sign of each of its terms:

- (18 + 4 m)

- 18 - 4 m

3 - 18 - 4 m = m

ⓘ Start from

3

and move back

18

on the number line, going below zero:

3 - 18

-15

- 15 - 4 m = m

ⓘ We gather the terms in

m

on the right and the other terms on the left

-15 = m + 4 m

ⓘ Like terms are grouped by adding their coefficients:

m + 4 m

5 m

-15 = 5 m

ⓘ Both sides are divided by

5

m = - \frac{15}{5}

ⓘ We simplify the fraction by dividing the numerator and the denominator by

5

, their greatest common divisor:

- \frac{15}{5}

-3

▶Solution found:

m = -3