Frankie buys some stamps. She spends £9.90 on 20p and 50p stamps.
She buys twice as many 20p stamps
as 50p stamps.
How many 20p stamps did she buy?

22

Step-by-step explanation:

£9.90 = 990p

x is number of 50p stamps

2x* 20 + x* 50 = 990

40x+50x = 990

90x = 990

x = 11

2x = 22

11 50p stamps

22 20p stamps

check:

11*50+22*20 = 550 + 440 = 990

37.16

Step-by-step explanation:

Find the area of the square, 8x7=56.

Then use the formula 2πr which is 2x3.14x3=18.84.

And finally, to calculate the area of the shaded region, subtract the area of the square and the area of the circle.

56-18.84=37.16.