Question 269813
(i) {{{D + Q = 60}}}
(ii) {{{10D + 25Q = 945}}}
step 1 - multiply (i) by -10 to get
(iii) {{{-10D - 10Q = -600}}}
step 2 - add (ii) and (iii) to get
(Iv) {{{15Q = 345}}}
step 3 - divide by 15 to get
{{{Q = 23}}}
This means
{{{D = 37}}}