We can find the value of an expression when given the values of \(x\), \(y\), etc.
Before we start, we will need to remind ourselves of BODMAS: the order in which we carry out calculations.
Find the value of \(3x + 5y\) when \(x = 2\) and \(y = -1\).
To find the value of an expression, we need to substitute the given values for \(x\) and \(y\) into \(3x + 5y\).
\[3x + 5y\]
\[ = 3 \times 2 + 5 \times ( - 1)\]
Remember, BODMAS tells us to multiply before we add.
\[= 6 + ( - 5)\]
Evaluate \(5c - b + 2a\) when \(a = 3\), \(b = 1\) and \(c = 4\).
\[5c - b + 2a\]
\[= 5 \times 4 - 1 + 2 \times 3\]
\[= 20 - 1 + 6\]
An approximate formula which converts celsius temperatures to farenheit is \(F = 2C + 30\).
Calculate \(F\) when \(C\) is 15.
\[F = 2C + 30\]
\[F = 2 \times 15 + 30\]
\[F = 30 + 30\]
\[F = 60\]
Therefore 15°C is approximately equal to 60°F.