PLUG in the numbers
4.5=500 x R x 2.5
divide both sides by 500
0.009=R x 2.5
divide 2.2 to both sides
R=.0036
In percent you have to multiply by 100 which is 0.36%
Let the number be Y .
Y is seven
less than 5 times another (let that other be X)
Y=7-5X
sum of both Y and X minus 4 gives one
Y+X-4=1
now solve both equations .