110 because avg speed is total distance over total time
The answer is: (z - 6)(z + 15)
z² + 9z - 90 = z*z + 15z - 6z - 6*15 =
= (z*z + 15z) - (6z + 6*15) =
= z(z + 15) - 6(z + 15) =
= (z - 6)(z + 15)
Answer:
Step-by-step explanation:
4.5x=90
x=20 history
28 chemistry
42 math
They add to 90.
History test=x
Chemistry test=1.4x
Math test=(1.5)(1.4)=2.1x
They add to 90