The order of operations is a collection of rules that gives the correct sequence of steps for doing a calculation. BIDMAS is an acronym used to tell you the correct order to complete a calculation when there are different operations . It stands for Brackets, Indices , Division, Multiplication, Addition and Subtraction.
Thus solving the expression;
we first solve all the multiplication parts:
7 x 6 - 5 x 4 + 1 x 3
Now addition:
= 42 - 20 + 3
Lastly subtraction:
= 42 - 23
= 19