3a+7b -1,5a - 2,8b

To simplify the expression 3a + 7b - 1.5a - 2.8b, you can combine like terms by adding or subtracting coefficients.

The expression can be rearranged as: (3a - 1.5a) + (7b - 2.8b) - 1

Combining the like terms for each variable: 1.5a + 4.2b - 1