x+(5/16)x=7/8(21/16)x=7/8(3/4)x=½x=2/3
x+5x/16=7/821x/16=7/8x=7/8 *16/21x=2/3
解：方程得x+5/16x=7/821/16x=7/8x=7/8÷21/16x=7/8×16/21x=2/3
