90 juniors took different sat-ii tests. 40% more students took chemistry than history, and 50% more students took math than chemistry. how many students took each test?
students took history test
took chemistry test
took math test

20 Students took History Test

28 Students took Chemistry Test

42 Students took Math Test

Step-by-step explanation:

Let

x > Students that took History Test

y ---> Students that took Chemistry Test

z > Students that took Math Test

we know that

x+y+z=90 > equation A

y=1.40x > x=y/1.40 > equation B

z=1.50y > equation C

substitute equation B and equation C in equation A and solve for y

(y/1.40)+y+1.50y=90

Multiply both sides by 1.40

y+1.40y+2.1y=126

4.5y=126

y=28

Find the value of x

x=y/1.40 > x=28/1.4=20

Find the value of z

z=1.50y > z=1.50(28)=42

therefore

20 Students took History Test

28 Students took Chemistry Test

42 Students took Math Test

-2

7 - 9 = -2

reversed:

-2 + 9 = 7

hdjd

step-by-step explanation: