9 dived by 3 = 3
so he surfed for 3 hours = 1/3 of 9
and there are 6 hours left
so he spent 6 hours building a sandcastle
Sin(x) = base / hypotenuse
sin(x) = 7/9
x = arcsin(7/9)
x = 51 degrees
The solutions would be 3 and 9
-5x+4y=11
substitute for x which is 5
(-5)(5)+4y=11
simplify :
4y-25=11
add 25 on both sides
4y-25=11
+25 +25
the 25 cancels out
so it would be 4y=36
and you divide both sides by 4
4/4 =36/4
which gives you (5,9)
x= 5 , y =9