It is known that a > b > 0, C > d > 0, a of B = C of D. it means that ① (a + b) / a = (c + D) / C. ② (a-b) / b = (C-D) / d Please use the eighth grade knowledge of Shandong education press to answer, thank you

It is known that a > b > 0, C > d > 0, a of B = C of D. it means that ① (a + b) / a = (c + D) / C. ② (a-b) / b = (C-D) / d Please use the eighth grade knowledge of Shandong education press to answer, thank you

(1)
∵a/b=c/d,∴a/b+1=c/d+1,∴(a+b)/b=(c+d)/d.
(2)
∵a/b=c/d,∴a/b-1=c/d-1,∴(a-b)/b=(c-d)/d.