40 * 5/8 = 200/8 = 25
they are 25 buttons
step-by-step explanation: x is an even number. x+2 is the next even number, x+4 is the third even number in the set, x+6 is the fourth, x+8 is the fifth. x+x+2+x+4+x+6+x+8=100. so 5x+20=100. 100-20=5x+20-20. 80=5x. x=16.
the area of a right triangle is 1/2 the area of a rectangle with the same dimensions
the triangle has a base of 12 and a height of 5
a rectangle of length 12 and a height 5 will be twice the area