70% of 100 is 70 students.
Unfortunately I can not make a model for you but here's an idea:
Draw a large circle.
Next, draw a line halfway down the circle, and halfwar down draw another line to the right, this making it look like three fourths.
Then, color the larger space in one color and the other smaller space that looks like a small slice of pie in another color.
On the larger piece write "70% who got an A" and on the smaller write "30% who didn't get an A"
At the bottom you can write 70 students out of 100 got an A on the test.
