(3/8x-15)/(5/8x-15)=7:5
问题描述:
(3/8x-15)/(5/8x-15)=7:5
答
内项积等于外项积
所以7(5/8x-15)=5(3/8x-15)
35/8x-105=15/8x-75
35/8x-15/8x=105-75
20/8x=30
x=30÷20/8
x=12