33
7 girls wore mask so 7
15-9 is how many boys wore mask so 6
7+6= 13
20+ 13 is 33
X will be the speed of species b and 4x will be the speed of species a:
x + 4x = 180
5x = 180
x = 180 / 5
x = 36 m/h
If species b has a speed of 36 m/h, the speed of species a is 4 times that:
4 x 36 = 144 m/h.
Answer:

Hope it helped,
Happy homework/ study/ exam!
1.Simplify.
-2{x}^{2}-4x+13+12{x}^{2}+2x-25−2x2−4x+13+12x2+2x−25
2.Collect like terms.
(-2{x}^{2}+12{x}^{2})+(-4x+2x)+(13-25)(−2x2+12x2)+(−4x+2x)+(13−25)
3.Simplify.
10{x}^{2}-2x-1210x2−2x−12
Answer:
75.391
Step-by-step explanation:
193x100/256=75.391
Pythagorean theorem
c2 = a2 + b2
71^2 = 43^2 + b2
5041 = 1849 + b2
3192 = b2
b = 56.5 which is answer choice d