First, let’s get the area of the base. To do that, we multiply 9 times 5, which gets us 45. Next, for the two sides of the triangular prism, take 7 times 5, which is 35, and multiply that by two, getting 70. Next, for the two triangles, we have to use the triangle surface area formula, which is 1/2•base•height. So, take the base and the heigh, 9, and 6, and you get 54. Since there are two triangles, we don’t have to divide it by 2. So, we add all of our sides, 54, 70, and 45, and we get 169 sq cm.
To find the number of girls signed up for camp, we just subtract the number of boys from to total number of children. There are 132 boys and 219 children, which gives us
219 - 132 = 87 girls. To find how many boys there are than girls, we just find the difference between the 132 boys and 87 girls by subtracting again:
