Evaluating expressions with and without changing the subject | Maths

Starter quiz

Substitute means to put in place of another. In algebra, substitution can be used to replace __________ with values.
- constants
- equations
- solutions
- variables ✓
$A={1\over2}(a+b)h$ is the formula for area of a trapezium. It can be rearranged to ${2A\over{h}}-a=b$ in order to make $b$ the ______ of the formula.
- 'subject' ✓
The formula for area of a triangle is $A={1\over2}bh$ . The area of a triangle with base 7.5 cm and height 6 cm is ______cm²
- '22.5' ✓
The formula $s={d\over{t}}$ can be rearranged to $t={d\over{s}}$ or $d=s\times {t}$ . If $d=12$ and $s=3$ , find $t$ .
- $36$
- $4$ ✓
- ${1\over{4}}$
Find the area of a trapezium with $h=7$ , $a=3.2$ , $b=4.8$ .
- $A={1\over2}(3.2+4.8)+7=11$ square units
- $A={1\over2}(3.2+4.8)\times7=28$ square units ✓
- $A=2(3.2+4.8)\times7=112$ square units
- $A={1\over2}(3.2\times4.8)\times7=53.76$ square units
$A={1\over2}(a+b)h$ is the formula for area of a trapezium. Select all the correct rearrangements of this formula.
- ${2A\over{h}}-b=a$ ✓
- ${Ah\over{2}}-a=b$
- ${A\over{2h}}-a=b$
- ${2h\over{A}}-a=b$
- ${2A\over{a+b}}=h$ ✓