Petunia bought two plants. She placed the first plant, which was 20 inches tall, on the windowsill. She noticed that the plant was growing at the rate of 1 inch per week.
y = x + 20
She placed the second plant, which was 5 inches tall, on the coffee table. She noticed that it was growing at the rate of 2 inches per week.
y= 2x + 5
The heights of the two plants are shown in the graph below.
How many weeks will it take for the plants to reach the same height?
5
20
10.
15
The equation for the height of the first plant is y = x + 20 and for the second plant is y = 2x + 5. To find when the two plants reach the same height, we need to set the two equations equal to each other and solve for x:
x + 20 = 2x + 5
Subtracting x from both sides, we get:
20 = x + 5
Subtracting 5 from both sides, we get:
15 = x
Therefore, it will take 15 weeks for the two plants to reach the same height. The correct answer is 15.