What is the value of 5b - 7 when b = 2?

The value of 5b - 7 when b = 2 is 3.

To find the value of the expression 5b - 7 when b is given as 2, we need to substitute the value of b into the expression. This means wherever we see 'b' in the expression, we replace it with 2. So, the expression 5b - 7 becomes 5(2) - 7.

Next, we perform the multiplication first, as per the order of operations (BIDMAS/BODMAS: Brackets, Indices, Division and Multiplication, Addition and Subtraction). Multiplying 5 by 2 gives us 10. Now, the expression is simplified to 10 - 7.

Finally, we perform the subtraction. Subtracting 7 from 10 gives us 3. Therefore, the value of the expression 5b - 7 when b = 2 is 3.

This process of substituting a given value into an algebraic expression and simplifying it step-by-step is a fundamental skill in GCSE Maths. It helps in understanding how variables work and how to manipulate algebraic expressions. Remember to always follow the order of operations to ensure you get the correct result.