An idea's worth is zero, it is the execution that matters.
Other way to look at it is if they are offering you 15% and keep 85% for them, without an mvp or revenue how are they justifying having 5.6 times more equity than you.
The only possible justification is the few thousand dollars that they have put in, you can either match that or maybe take slightly less equity to offset that amount based on the expected valuation.
But please do not settle for less than equal split, because you will be putting the same amount of effort in the execution of the idea.
https://www.ycombinator.com/library/5x-how-to-split-equity-a...
It should be equal split.
An idea's worth is zero, it is the execution that matters.
Other way to look at it is if they are offering you 15% and keep 85% for them, without an mvp or revenue how are they justifying having 5.6 times more equity than you.
The only possible justification is the few thousand dollars that they have put in, you can either match that or maybe take slightly less equity to offset that amount based on the expected valuation.
But please do not settle for less than equal split, because you will be putting the same amount of effort in the execution of the idea.