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

77

step-by-step explanation:

3

step-by-step explanation:

in standard form:

a= dictionaries

b= maps

you have to buy 3 dictionaries, so put a 3 next to the a (dictionaries) so that you can multiply them by each other.

a3+b= 60 (the amount of money you have)

we already know the cost of a=15 so replace a with $15

($15 x 3)+b=60

multiply 15 and 3 to get $45 and replace it with $45

45+b=60

and then replace b with 15 to get the total:

45+15=60

that means you have $15 left after buying 3 dictionaries.

15 divided by the cost of a map ($5) equals 3.

so you can buy 3 maps.

sorry if it was confusing!