Show that a, b,c, d are in proportion if 2a^2+3b^2:2c^2+3d^2::2a^2-3b^2:2c^2 -3d^2​

Marco has $38.43 dollars in his checking account. his checking account is linked to his amazon music account so he can buy music. the songs he purchases cost $1.29. part 1: write an expression to describe the amount of money in his checking account in relationship to the number of songs he purchases. part 2: describe what the variable represents in this situation.

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What is the radius of a circle with an area of 78.5 cubic inches? use 3.14 for pie