39 x 5 = (30 x 5) + (9 x 5) = 150 + 45 = 195
He did not change the sign of operation when 28 crossed the equals sign.
Answer:
21 girls.
Step-by-step explanation:
50% of 42 students are girls.
So 42/2 = 21.
Therefore 21 of the students are girls.
<em>Hope I helped</em>
Since, the polygon is a trapezoid made up of a rectangle and a right triangle. Therefore, according to the question, the figure of the polygon is attached.
Since, perimeter is the total length of the outer boundary of the figure. Therefore,
Perimeter of the polygon is


Area of the polygon = Area of Rectangle + Area of Triangle
![=[(18) \times (15)] + [(\frac{1}{2}) \times (8) \times (15)]](https://tex.z-dn.net/?f=%3D%5B%2818%29%20%5Ctimes%20%2815%29%5D%20%2B%20%5B%28%5Cfrac%7B1%7D%7B2%7D%29%20%5Ctimes%20%288%29%20%5Ctimes%20%2815%29%5D)
![=270 + [(\frac{8}{2}) \times (15)]](https://tex.z-dn.net/?f=%3D270%20%2B%20%5B%28%5Cfrac%7B8%7D%7B2%7D%29%20%5Ctimes%20%2815%29%5D)
![=270 + [4 \times (15)]](https://tex.z-dn.net/?f=%3D270%20%2B%20%5B4%20%5Ctimes%20%2815%29%5D)


Given, the ratio of blocks A, B, C,D are in the ratio 4:7:3:1
Let us consider the common ratio to be ‘x’.
So, toy blocks with alphabet A is 4x and
toy blocks with alphabet B is 7x and
toy blocks with alphabet C is 3x and
toy blocks with alphabet D is x
Again, the number of ‘A’ blocks is 50 more than the number of ‘C’ blocks.
As no. of ‘A’ and ‘C’ blocks are 4x and 3x respectively.
So,
4x=50 + 3x
x=50
Thus, the number of ‘B’ blocks is 7x = 7(50) = 350
350 is the required number.