(3×m-20):5=50 480:(13-t)+20=100

1. (3m - 20) : 5 = 50, (3m-20) = 50*5 (3m-20)=250 3m=250+20 3m=270 m=270:3 m=90, 2. 480:(13-t)+20=100, 480:(13-t)=100-20=80, 13-t=480:80=6, t=13-6, t=7