Answer is 9.11 weeks
( or rounded up to 10 weeks depending on the instructions. 9 will be short of her goal, 10 will be over her goal)
Step by step
We can use y intercept to find this
y = mx + b
We know y = $560 needed
We know the rate (m) is $45 per week
We know her starting point (b) is $150
$560 = $45x + $150
Subtract 150 from both sides to isolate variable x
$560 - 150 = $45x + 150 - 150
$410 = $45x
Now divide both sides by 45 to solve for x
$410/45 = 45/45 x
X = 9.11 weeks