book Maths Puzzle Numerical Ability

Im learning about factoring Trinomials by grouping and there is one problem I am having some trouble with. its 4r2(the 2 is the exponent) + 3r - 10

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Hi, im Very confused on Linear Graphs anything to do with it.
First here is a problem the i have that i cannot understand at all
{2x+y=-3
{ y= 7
and it says "use substitution to solve the problem"
.1166meg ohms/ 1/.22meg ohms + 1/1meg ohms + 1/x
how do I solve for x?