3(x + 10) < 2 (20 – x)
Distributing multiplication over the addition and the subtraction, we get:
3x + 3*10 < 2*20 - 2x
3x + 30 < 40 - 2x
30 is adding on the left, then it will subtract on the right.
2x is subtracting on the right, then it will add on the left.
3x + 2x < 40 - 30
5x < 10
5 is multiplying x on the left, then it will divide on the right.
x < 10/5
x < 2