Given: 9x - 10y = 21,

To Prove: The given equations have infinitely many solutions.

Proof:

We know that the general form for a pair of linear equations in 2 variables x and y is a₁x + b₁y + c₁ = 0

and a₂x + b₂y + c₂ = 0.

Comparing with above equations,

we have a₁ = 9,

b₁ = - 10,

c₁ = - 21;

a₂ = 3/2 ,

b₂ = - 5/3

c₂ = - 7/2

Since

The lines are coincident.

The given equations have infinitely many solutions.