VTMO 2013 — Grade 5 — semifinal Question 7

Question 7

Find the black area: base width $5 \,\mathrm{cm}$, two vertical sides $4 \,\mathrm{cm}$, and top height $10 \,\mathrm{cm}$ as shown.

Question illustration

$20 \,\mathrm{cm}^{2}$
$25 \,\mathrm{cm}^{2}$
$35 \,\mathrm{cm}^{2}$
$40 \,\mathrm{cm}^{2}$
$50 \,\mathrm{cm}^{2}$