Question Number 120559 by A8;15: last updated on 01/Nov/20
Commented by A8;15: last updated on 01/Nov/20
find red surface
Answered by mr W last updated on 01/Nov/20
Commented by mr W last updated on 01/Nov/20
$${in}\:{both}\:{diagrams}\:{the}\:{shaded}\:{area}\:{is} \\ $$$${the}\:{same},\:{i}.{e}.\:{half}\:{of}\:{the}\:{total}\:{area} \\ $$$${of}\:{the}\:{parallelogram}. \\ $$
Commented by A8;15: last updated on 01/Nov/20
thanks
Commented by mr W last updated on 01/Nov/20
Commented by mr W last updated on 01/Nov/20
$${A}+{B}+\mathrm{72}+{C}+\mathrm{8}={B}+\mathrm{79}+{C}+\mathrm{10} \\ $$$${A}+\mathrm{72}+\mathrm{8}=\mathrm{79}+\mathrm{10} \\ $$$$\Rightarrow{A}=\mathrm{9} \\ $$