<PRE><B>Question 1031449</B>
Let L = number of 20c coins
Let S = number of 10c coins
20*L + 10*S = 1770
L + S = 124 coins
Solve for S by adding -L to each side
S = 124 - L
substitute (124 - L) for S in 20*L + 10*S = 1770
20*L + 10*(124 - L) = 1770
20L + 1240 -10L = 1770
10L + 1240 = 1770
add -1240 to each side
10L = 530
divide each side by 10
L = 53
Since S = 124 - L , S = 124 - 53 
S = 71
71 * 10c = 710c
53 * 20c = 1060c
The total is 1770c
So we have 53 20c coins and 71 10c coins.</PRE>