How do you use proportions to solve percent problems

Step-by-step explanation:

EXAMPLE #1:

What number is 75% of 4?   (or   Find 75% of 4.)

The PERCENT always goes over 100.

   (It's a part of the whole 100%.)

4 appears with the word of:

   It's the WHOLE and goes on the bottom.

A proportion showing one fraction  with PART as the numerator and 4 as the denominator equal to another fraction with 75 as the numerator and 100 as the denominator.

We're trying to find the missing PART (on the top).

In a proportion the cross-products are equal:   So 4 times 75 is equal to 100 times the PART.

The missing PART equals 4 times 75 divided by 100.

(Multiply the two opposite corners with numbers; then divide by the other number.)

4 times 75=100 times the part

300=100 times the part

300/100=100/100 times the part

3=   the part

A proportion showing the denominator,  4, times the diagonally opposite 75; divided by  100.

-3

step-by-step explanation:

a drawing really does here:

so i draw the horizontal line y=2 and the vertical line x=-2 at this intersection i put b (this is where my right angle is going to be).   so point b is at (-2,2).   point a is 5 units long and is also on y=2 so this point has to be (3,2) or (-7,2) -doesn't matter i will go with (3,2).

now we know c is at (-2,y) we don't know the y yet bet we know that c is on x=-2.

we have the area of the triangle is .5bh=12.5

we know the base length is 5 (ab)

we have the height is (2-y) if you look at your

plug in

.5(5)(2-y)=12.5

solve for y to get the y-coordinate for c

2.5(2-y)=12.5

divide both sides by 2.5 giving:

2-y=5

now subtract 2 on both sides

-y=3

y=-3