Her brother sent C. 490 messages.
In order to find this, we need to set it up as a proportion. Once we have done that, we can cross multiply and solve for the unknown variable.
(4/7) = (280/x) -----> Cross multiply.
4 * x = 7 * 280
4x = 1960
x = 490
The answer is c, since they both add up to 90°
Answer:Joanie watched 4/15 of the movie at night
Step-by-step explanation:
Let total amount of movie to watch = 1 whole since we are dealing with fractions
Amount of movie watched in the morning = 1/3
Amount watched at night = x
Amount remaining= 2/5
so that Total amount of movie to watch - Amount watched in morning and night = Amount remaining to watch
1 - ( 1/3 + x ) = 2/5
1- 2/5 = 1/3 + x
3/5 =1/3 + x
3/5 - 1/3 = x
9- 5/15 = x
x= Amount watched at night = 4/15
X - 2y = 3
<span>4x^2 - 5xy + 6y = 3
lets solve for x the first and substitute in the second:
x = 3 + 2y
4(</span>3 + 2y)^2 - 5(3 + 2y)y + 6y = 3
4(9 + 12y + 4y^2) - 15y - 10y^2 = 3
36 + 48y +16y^2<span> - 15y - </span><span>10y^2 = 3
6y^2 + 33y + 33 = 0
we can solve using the general quadratic formula:
y = (-33 +- </span>√(33^2 - 4*6*33)<span>)/12
</span>y = (-33 +- √(297)<span>)/12
</span>so there are 2 solutions for y:
y1 = (-33 + √(297)<span>)/12
</span>y2 = (-33 - √(297)<span>)/12
</span>pick one and then substitute the y value in the first equation to find x
