Question 58388
d = 5n + 1
4n = p
10d + 5n + p = 777
10(5n + 1) + 5n + 4n = 777
50n + 10 + 5n + 4n = 777
59n = 777
n = 13
d = 66
p = 52
check
10(66) + 5(13) + 52 = 777
660 + 65 + 52 = 777
777 = 777
OK