Question

Which is the best estimate of x based on rounding the constants and coefficients in the equation to the nearest integer? 3.1x + 5.2 = 9.9

Answer 1

You'd round 3.1 down to 3, 5.2 to 5, and 9.9 to 10.
3x+5=10
-5 on both sides
3x=5
divide by 5
x= 5/3.

I don't know what your options are, but that's the solution.