The building blocks of geometry would be point line and plane.
C
First you -4 from x so you have to do the opposite which is to add 4
so what you do is distribute the 0.9 to x and 1.4 to get 0.9x+1.26 then combine like terms 1.9x - 1.04= 1.6 then add 1.04 to both sides to get 1.9x = 2.64 divide 1.9 to both sides
answer:1.389 and if you round 1.39