7)
[tex]total \: increase \: for \:sides \: of \: the \: equillateral \: triangle = 3 \times 5cm = 15cm \\ perimeter \: of \: an \: equillateral \: triangle = 3 \times length \: of \: one \: side \\ originl \: perimeter = incresed \: perimeter - increase = 60cm - 15cm = 45cm \\ one \: side \: of \: the \: equillateral \: triangle = 45cm \div 3 = 15cm[/tex]
8b)
[tex]let \: x \: represent \: the \: amount \: each \: person \: has \: in \: the \: end. \\ 40 - 4(7.50) = 4x \\ 40 - 30 = 4x \\ 10 = 4x \\ 4x = 10 \\ x = 10 \div 4 \\ x = 2.5 \\ each \: boy \: has \: 2.50 \: in \: the \: end[/tex]
