In a school gym, the ratio of the number of boys to the number of girls was 4: 3 . after 160 boys left the gym, the ratio became 4: 5. how many girls were there in the gym?

300 girls were there in the gym.

Step-by-step explanation:

Given:

The ratio of the number of boys to the number of girls was 4:3, after 160 boys left the gym, the ratio became 4:5.

Now, to find the number of girls in the gym.

The girls in the gym does not left, their quantity is same before and after.

So, we multiply the both ratios to make the girls ratio same:

4:3 × 5 = 20:15

4:5 × 3 = 12:15

Now, we find the units of the ratio.

The ratio of boys dropped down by 160:

20 - 12 = 8 units.

160 = 8 units

Now, dividing both sides by 8 we get:

20 = 1 unit

So, 1 unit = 20.

Now, girls = 15 units

So, 15 × 20 = 300.

Therefore, 300 girls were there in the gym.

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18