Graphing systems of linear equations

Question

The sum of Sherance and John’s ages is 70. John is four times as old is Sharon. If you let S equal share his age and TJ equal John’s age then the problem can be represented by a system of equations. Which of the following shows a graph of the system and the solution to this problem

Answer 1

Let Sherance's Age = S and John's Age = J

The sum of Sherance and John’s ages is 70.

S + J = 70

John is four times as old is Sharon.

J = 4S

Which of the following shows a graph of the system and the solution to this problem?

We can pretend S = x and J = y, then we can visualize this as

x + y = 70 and y = 4x

The graph of the system of equations is the graph of two lines, x + y = 70 has a y-intercept of 70 and a slope of -1. The line y = 4x has a y-interecept at (0,0) and a slope of 4. They intersect at (14, 56).