Do the two inner parentheses first
$${\mathtt{10}}{\mathtt{\,\times\,}}{\mathtt{4}} = {\mathtt{40}}$$
$${\mathtt{7}}{\mathtt{\,\times\,}}{\mathtt{5}} = {\mathtt{35}}$$
subtract what is in the outer most parentheses
$${\mathtt{40}}{\mathtt{\,-\,}}{\mathtt{35}} = {\mathtt{5}}$$
add what is left outside the parentheses
$${\mathtt{5}}{\mathtt{\,\small\textbf+\,}}{\mathtt{5}} = {\mathtt{10}}$$
Do the two inner parentheses first
$${\mathtt{10}}{\mathtt{\,\times\,}}{\mathtt{4}} = {\mathtt{40}}$$
$${\mathtt{7}}{\mathtt{\,\times\,}}{\mathtt{5}} = {\mathtt{35}}$$
subtract what is in the outer most parentheses
$${\mathtt{40}}{\mathtt{\,-\,}}{\mathtt{35}} = {\mathtt{5}}$$
add what is left outside the parentheses
$${\mathtt{5}}{\mathtt{\,\small\textbf+\,}}{\mathtt{5}} = {\mathtt{10}}$$
