the last one: x/2=45; x = 90
the problem says: half of a number is 45.
let's use x to represent this number
we know that dividing by 2 halves a number, so, x/2 = 45
to get x alone, we multiply 2 by 2 to cancel it out. so, multiply by 2 on both sides
x/2 • 2 = 45 • 2
x = 90
hope this helped!