Question

Me ajudem,o mais rapido,pfvr

Answer 1

a) 12+9+x=90
x=-12-9+90
x=69


b)5+4+x=90
x=-5-4+90
x=81

c)8+10+x=90
x=-8-10+90
x=72

d)20+3x+4x=90
3x+4x=-20+90
7x=70
x=70/7
x=10