So many of my students are having difficulty with two-digit subtraction. In other words. A linear Diophantine equation is an equation between two sums of monomials of degree zero or one.
The equation 2 x 5 9 is conditional because it is only true for x 7.
When you balance equations its a good idea to check your work by multiplying the subscript of each atom by the coefficient. V stands for volume l for length w for width and h for height. In the pictures below each circle represents one and the block represents the unknown x. We now have an equation which is a number sentence in which a variable takes the place of unknown information.