A, x*12-x*4=222
x(12-4)=222
x*8=222
x=222:8
x=27,75
B,x*13,7+x*87,3-x=17
x*13,7+x*87,3-x*1=17
x(13,7+87,3-1)=17
x*100=17
x=17:100
x=0,17
a, x. 12 - x.4 = 222
x.( 12 - 4 ) = 222
x. 8 = 222
x = \(\frac{111}{4}\)
b, x. 13,7 + x. 87,3 - x = 17
x.( 13,7 + 87,3 - 1 ) = 17
x. 100 = 17
x = 0,17