Step-by-step explanation:
4x+5y=4 (equation 1)
2x-y=9 (equation2)
solving equation 1 and 2 and multiplying equation 2 by 2
4x+5y=4
4x-2y=18
- + -
________
7y= -14
y= -2
putting the value of y in equation 2
2x-y=9
2x+2=9
2x=7
x=3.5
Step-by-step explanation:
an object and its shadow create a right-angled triangle.
2 objects and their shadows create 2 similar right-angled triangles.
that means the angles are the same, and the side lengths of one triangle all correlate with the corresponding side lengths of the other triangle via the same factor.
so,
42 × f = 6
f = 6/42 = 1/7
the length of Joel's shadow is then
20 × f = 20 × 1/7 = 2.857142857... ft
5/8÷1/3=5/8×3/1
(multiply by reciprocal instead of dividing)
5/8×3/1=15/8=1.875