There are 765 marbles in a box. there are twice as many blue marbles as green marbles. there are three times as many red marbles as blue. how many blue marbles are there in the box?

B=blue
g=green
r=red
2 times as many blue as green
b=2g
3 times as many red as blue
r=3b
subsitute 2g for b
r=3(2g)=6g
r=6g

r+g+b=765
so we subsitute
r=6g
g=g
b=2g

6g+g+2g=765
add like terms
9g=765
divide both sides by 9
g=85
subsitute
b=2b
b=2(85)
b=170

170 blue

Answer: d. 39 cmin the diagram, the approximate length of the minor arc de is 39 centimetres.step-by-step explanation: the formula for the length of an arc in a circle is as displayed below.let the length of the minor arc de = xx = 2( pi )r × angle of sector / 360°from this, we will substitute the values given from the problem into the formula to obtain the length of the minor arc de.x = 2( pi )r × angle of sector / 360°r = radius = 25cmpi as an approximate value = 3.14angle of sector = 120°x = 2( 3.14 )( 25 ) × 120° / 360°x = 157 × 1 / 4x = 39.25x = 39 ( rounded to the nearest whole number as an approximate value )