first find the value of x
since abcd is a rhombus, all sides should be equal, meaning 4x + 14 equals 7x + 1
put them into a simultaneous equation and solve for x
4x + 14 = 7x + 1
14 - 1 = 7x - 4x
13 = 3x
x = 13 ÷ 3
x = 4.333
substitute this value into 7x + 1 or 4x + 14
7 ( 13 ÷ 3 ) + 1 = 31.333 or 94 ÷ 3