find r from the formula e= ir when e= 20 and i = 4

plug in the numbers

so

20=4r

then divide by 4

20/4

so 5=r

e= ir

20 = 4r

20/4 = r
5 = r

Substitute 5 for r to prove this equation.

20 = 4 * 5
20 = 20

Right.

To find the value of "r" in the formula e = ir when e = 20 and i = 4, you can rearrange the formula and solve for "r". The formula can be rearranged as follows:

e = ir

Divide both sides of the equation by "i" to isolate "r":

e/i = r

Now you can substitute the given values into the equation:

r = 20/4

Simplifying the division:

r = 5

Therefore, when e = 20 and i = 4, the value of r is 5.