Answer:
ak - kr k(a - r)
x = -------------- or x = ------------
7 7
Explanation:
1. Multiply all three terms by k to eliminate the fraction:
ak = 7x - kr
2. Subtract kr from both sides:
7x = ak - kr
3. Divide both sides by 7:
ak - kr k(a - r)
x = -------------- or x = ------------
7 7