Answer:
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
