Given: Area of the rhombus = 120 cm2
Length of one diagonal = 10 units
Length of the other diagonal = (7x + 3) units
Area of a rhombus = 12×(product of diagonals)
⇒120=12×10×(7x+3)
⇒120=5×(7x+3)
⇒(7x+3)=1205=24
⇒7x=21
⇒x=3
Therefore, the value of x is 3 units.