Calculate: -4m-16=-4(1+2m)+8

Expression: $-4m-16=-4\left( 1+2m \right)+8$

Distribute $-4$ through the parentheses

$-4m-16=-4-8m+8$

Calculate the sum

$-4m-16=4-8m$

Move the variable to the left-hand side and change its sign

$-4m-16+8m=4$

Move the constant to the right-hand side and change its sign

$-4m+8m=4+16$

Collect like terms

$4m=4+16$

Add the numbers

$4m=20$

Divide both sides of the equation by $4$

$m=5$