By solving a system of equations, we will see that the area of painting P is 2,600 cm^2
How to get the area of painting P?
Remember that the area of a rectangle of length L and width W is:
A = L*W
Then the area of painting P is:
A = 40cm*(3x - 10)cm
The area of paint Q is:
A' = (30 cm)*(x + 15)cm
And que know that:
A = A' + 1400cm^2
Then we havea system of equations:
A = A' + 1400cm^2
A = 40cm*(3x - 10)cm
A' = (30 cm)*(x + 15)cm
First, we can replace the third equation into the first one to get:
A = (30 cm)*(x + 15)cm + 1400cm^2
And that must be equal to:
A = 40cm*(3x - 10)cm
So now we can solve:
40cm*(3x - 10)cm = (30 cm)*(x + 15)cm + 1400cm^2
for x.
It gives:
120cm*x - 400cm^2 = 30cm*x + 1850 cm^2
120cm*x - 30cm*x = 1850cm^2 + 400cm2
x = (2250cm^2)/(90cm) = 25cm
Now that we know x, we can get the area of painting P.
A = 40cm*(3*25cm - 10cm) = 2,600cm^2
If you want to learn more about systems of equations, you can read:
https://brainly.com/question/13729904