Mae sells newspaper subscriptions door-to-door. In addition to a fixed salary, she earns a commission for each subscription that she sells. The table shows Mae’s total earnings, y (in dollars), from selling x newspaper subscriptions:

Subscriptions Sold and Earnings
Subscriptions Sold
(x) Total Earnings
(y)
1 135
2 145
3 155

Which equation best shows the relationship between x and y?

Question

Mae sells newspaper subscriptions door-to-door. In addition to a fixed salary, she earns a commission for each subscription that she sells. The table shows Mae’s total earnings, y (in dollars), from selling x newspaper subscriptions:

Subscriptions Sold and Earnings
Subscriptions Sold
(x)	Total Earnings
(y)
1	135
2	145
3	155

Which equation best shows the relationship between x and y?

Vocaloid · Answer

We don’t really need the choices here, but here they are just in case

y = 10x + 125
y = x + 135
y = 10x + 135
y = x + 10

Vocaloid · Answer

Recall that a generic linear equation is y = mx + b where m is the slope and b is the y-intercept.

The slope, m, is also the rate of change for the y values. So look at the table, when x increases by 1, how much does y change? That’s your m-value.

For your b-value, what would the y value be when x = 0? You can work from x = 1, y = 135 and subtract the rate of change to get the y value at x = 0. That ends up being your b-value.

Once you have m and b, plug them into y = mx + b to get your final equation.